Filtration media can be used to prevent undesirable vapors, particulate, or suspended droplets in a gas stream from escaping into the atmosphere. For example, whenever an oleo material or substances (e.g. grease, oil or fat) are heated, some will vaporize or form droplets. There is a desire to prevent such vaporized or droplet material from escaping into the air, unfiltered. Presently employed filtering media can include an aggregate of fibrous material, such as organic fiber mat or inorganic fiberglass, that extend over the traveling path of a vapor or liquid, such that the fibrous material catches the oleo vapors or droplets as they pass through the interstices of the filtering material. Although, initially, such filtering mechanisms may be capable of efficiently removing the oleo vapors or droplets from the air stream, the oleo vapors or droplets gather in the interstices of the filtering material in increasing quantities as the filtration process progresses, resisting the flow.
The flow rate of air through the filter immediately begins to decrease as the oleo material begins to collect on the filter media. This build-up of undesirable substances can substantially or completely block the flow of air and its load of material to be filtered through the filter, requiring frequent replacement of the filter. This replacement process typically requires a shut down of the mechanism that produces the vapor. Often times, the filter, upon having the undesirable substance collected thereon is disposed of without further use.
U.S. Pat. No. 5,776,354, issued to van der Meer et al., discloses a method for separating a dispersed liquid phase (i.e. an oil film) from a gas, using a filter bed of a particulate, porous polymer material whose size is on the order of 0.1 to 10 mm. Although van der Meer et al. teach that the dispersed liquid phase can fill into the pores of the particulate material, the particulate material is a polymer, thereby restricting the available methods for subsequently separating the liquid phase from the particulate material. In fact, van der Meer et al. only teach centrifugal force (i.e. a centrifuge) for separating the oil from particulate material. Thus, there remains need for filtration media that not only (1) ameliorate the problem of restricted airflow through the filter, but (2) also can undergo harsher filtrate-separation processes, yet subsequently retain its desired properties for repeated use.